Caplan's syndrome (or Caplan disease or rheumatoid pneumoconiosis) is a combination of rheumatoid arthritis (RA) and

pneumoconiosis Pneumoconiosis is the general term for a class of interstitial lung disease where inhalation of dust ( for example, ash dust, lead particles, pollen grains etc) has caused interstitial fibrosis. The three most common types are asbestosis, silicos ...

that manifests as intrapulmonary nodules, which appear homogeneous and well-defined on

chest X-ray A chest radiograph, called a chest X-ray (CXR), or chest film, is a projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures. Chest radiographs are the most common film taken in med ...

Signs and symptoms

Caplan syndrome presents with cough and shortness of breath in conjunction with features of rheumatoid arthritis, such as painful joints and morning stiffness. Examination should reveal tender, swollen metacarpophalangeal joints and

rheumatoid nodules A rheumatoid nodule is a lump of tissue, or an area of swelling, that appear on the exterior of the skin usually around the olecranon (tip of the elbow) or the interphalangeal joints (finger knuckles), but can appear in other areas. There are fou ...

;

auscultation Auscultation (based on the Latin verb ''auscultare'' "to listen") is listening to the internal sounds of the body, usually using a stethoscope. Auscultation is performed for the purposes of examining the circulatory and respiratory systems (hea ...

of the chest may reveal diffuse crackles that do not disappear on coughing or taking a deep breath. Caplan syndrome is a nodular condition of the lung occurring in dust-exposed persons with either a history of rheumatoid arthritis (RA) or who subsequently develop RA within the following 5–10 years. The nodules in the lung typically occur bilaterally and peripherally, on a background of simple

coal workers' pneumoconiosis Coal workers' pneumoconiosis (CWP), also known as black lung disease or black lung, is an occupational type of pneumoconiosis caused by long-term exposure to coal dust. It is common in coal miners and others who work with coal. It is similar to bo ...

. There are usually multiple nodules, varying in size from 0.5 to 5.0 cm. The nodules typically appear rapidly, often in only a few weeks. Nodules may grow, remain unchanged in size, resolve, or disappear and then reappear. They can cavitate, calcify, or develop air-fluid levels. Grossly, they can resemble a giant silicotic nodule. Histologically, they usually have a necrotic center surrounded by a zone of plasma cells and lymphocytes, and often with a peripheral inflammatory zone made of macrophages and neutrophils.

Causes

Caplan syndrome occurs only in patients with both RA and

related to mining dust (coal, asbestos, silica). The condition occurs in miners (especially those working in

anthracite Anthracite, also known as hard coal, and black coal, is a hard, compact variety of coal that has a submetallic luster. It has the highest carbon content, the fewest impurities, and the highest energy density of all types of coal and is the hig ...

coal-mines), asbestosis,

silicosis Silicosis is a form of occupational lung disease caused by inhalation of crystalline silica dust. It is marked by inflammation and scarring in the form of nodular lesions in the upper lobes of the lungs. It is a type of pneumoconiosis. Silicos ...

and other pneumoconioses. There is probably also a genetic predisposition, and

smoking Smoking is a practice in which a substance is burned and the resulting smoke is typically breathed in to be tasted and absorbed into the bloodstream. Most commonly, the substance used is the dried leaves of the tobacco plant, which have bee ...

is thought to be an aggravating factor.

Pathophysiology

The presence of rheumatoid arthritis alters how a person's immune system responds to foreign materials, such as dust from a coal mine. When a person with rheumatoid arthritis is exposed to such offensive materials, they are at an increased risk of developing pneumoconiosis.

Diagnosis

* Chest radiology shows multiple, round, well defined

nodules Nodule may refer to: *Nodule (geology), a small rock or mineral cluster *Manganese nodule, a metallic concretion found on the seafloor *Nodule (medicine), a small aggregation of cells *Root nodule Root nodules are found on the roots of plants, p ...

, usually 0.5-2.0 cm in diameter, which may cavitate and resemble tuberculosis. * Lung function tests may reveal a mixed restrictive and obstructive ventilatory defect with a loss of lung volume. There may also be irreversible airflow limitation and a reduced DLCO. *

Rheumatoid factor Rheumatoid factor (RF) is the autoantibody that was first found in rheumatoid arthritis. It is defined as an antibody against the Fc portion of IgG and different RFs can recognize different parts of the IgG-Fc. RF and IgG join to form immune com ...

antinuclear antibodies Antinuclear antibodies (ANAs, also known as antinuclear factor or ANF) are autoantibodies that bind to contents of the cell nucleus. In normal individuals, the immune system produces antibodies to foreign proteins (antigens) but not to human prote ...

, and non-organ specific antibodies may be present in the serum. *

Silicosis Silicosis is a form of occupational lung disease caused by inhalation of crystalline silica dust. It is marked by inflammation and scarring in the form of nodular lesions in the upper lobes of the lungs. It is a type of pneumoconiosis. Silicos ...

and asbestosis must be considered in the differential with TB.

Management

Once tuberculosis has been excluded, treatment is with

steroids A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...

. All exposure to coal dust must be stopped, and smoking cessation should be attempted. Rheumatoid arthritis should be treated normally with early use of DMARDs.

Prognosis

The nodules may pre-date the appearance of rheumatoid arthritis by several years. Otherwise prognosis is as for RA; lung disease may remit spontaneously, but pulmonary fibrosis may also progress.

Epidemiology

Incidence is currently 1 in 100,000 people but is likely to fall as the coal mining industry declines. It has also been shown to occur in cases of complicated silicosis (marked by progressive massive pneumoconiosis).

History

The syndrome is named after Dr. Anthony Caplan, a physician on the Cardiff Pneumoconiosis Panel, who identified the constellation of findings as a distinct entity in a 1953 publication. He followed this with further articles exploring the disease. Caplan syndrome was originally described in coal miners with

progressive massive fibrosis Progressive massive fibrosis (PMF), characterized by the development of large conglomerate masses of dense fibrosis (usually in the upper lung zones), can complicate silicosis and coal worker's pneumoconiosis. Conglomerate masses may also occur in o ...

References

External links

* {{DEFAULTSORT:Caplan Syndrome Syndromes affecting the respiratory system